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%I #26 Jul 16 2019 20:13:53
%S 3,7,5,3,17,11,3,5,7,3,29,47,3,2021546332693553,401,3,11,5,3,1013,31,
%T 3,5,27301567,3,23,419,3,179,7,3,13,5,3,61,1093,3,5,11,3,25665929,757,
%U 3,7,13,3,331,5,3,11,7,3,5,3613,3,17,6977,3,47,349,3,151,5,3,7
%N Smallest prime factor of 144396166620968*n + 1.
%C In 1951, A. Ferrier showed that every prime factor of N = (2^148 + 1)/17 is of the form 144396166620968*n + 1, n > 0. He also noted that the first 11 numbers of this form have prime factors under 30 and hence cannot be primes, which implies that N is prime.
%D Hans Riesel, Prime numbers and computer methods for factorization, Springer, New York, 2012, pp. 122-123.
%H Chai Wah Wu, <a href="/A228000/b228000.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FerriersPrime.html">Ferrier's Prime</a>
%t FactorInteger[#][[1,1]]&/@(144396166620968*Range[70]+1) (* _Harvey P. Dale_, Oct 24 2017 *)
%o (PARI) for(n=1, 65, print1(factor(144396166620968*n+1)[1, 1], ", "));
%o (Python)
%o from sympy import factorint
%o def A228000(n):
%o return min(factorint(144396166620968*n + 1)) # _Chai Wah Wu_, Jul 16 2019
%K nonn
%O 1,1
%A _Arkadiusz Wesolowski_, Oct 25 2013